Self-cleaning filter

ABSTRACT

Self-cleaning filter comprises a horizontal pressure unit mounted to rotate about a vertical axis. Counter-current cleaning occurs when both faces of a piston inside the pressure unit are subjected to the pressure within the filter, the extra pressure required to cause a flow of cleaning fluid being supplied by a spring which acts on the piston and is compressed when one face of the piston is vented to atmosphere.

United States Patent 1 1 Picard 1 Feb. 20, 1973 [54] SELF-CLEANING IL R3,388,799 6/1968 Rymer ..210 10s x [76] inventor: Marcel Picard, RuePasteur, Saint- Aguhn France Primary Examiner.lohn Adee [22] Filed: June28, 1971 Attorney-Holcombe, Wetherill & Brisebois [211 App]. No.:157,316

[57] ABSTRACT [30] Foreign Application Priority Data Self-cleaningfilter comprises a horizontal pressure July 9, 1970 France ..70254l9unit mounted to rotae about a vertical axis Counter; current cleaningoccurs when both faces of a piston "210/ inside the pressure unit aresubjected to the pressure [58] Fie'ld 332 333 within the filter, theextra pressure required to cause a flow of cleaning fluid being suppliedby a spring which 5 References Cited acts on the piston and iscompressed when one face of the piston is vented to atmosphere. UNITEDSTATES PATENTS 5 Claims, 7 Drawing Figures 3,283,903 ll/l966 Muller..2l0/108 n V is n r V 5 A! '9 2 MM A t -t on; one \\s\\\\\\\\\\\:,, 3r\\\\\\\\\\\\\\\\\\\\\\\k\\\\\\ -5 s 1 J t, s '111111111111111111 Q -428 y -11 4 -10 5 #9 IIIIIIIIIIIIII4 I/\\\\;\\\\/////// %ru\ 30 l-l ul 114 19 113,, d, ,r. -'-,"r i 'M 2 PATENTEB FEB 2 01975 SHEET 2 OF 4PATENTEB FEB 2 0 I973 SHEET 3 BF 4 SUMMARY OF THE INVENTION My priorapplication Ser. No. 792,696, filed in the United States on Jan. 21,1969 now US. Pat. No. 3,608,722, relates to a filter adapted to operateas either a static filter or an automatically self-cleaning filter andcharacterized by the fact that the pressure of the fluid being filteredis used to actuate an independent pressure unit which is readilyremovable and located at the upper part of the filter above a columnarfilter member, which member is also adapted to be easily removed withoutthe use of tools and without removing the principal inlet and outletducts.

One of the characteristics of this filter which has permitted theseresults to be attained is that the pressure unit is mounted to rotateabout a vertical axis and consists of a horizontal cylinder in which -apiston reciprocates from left to right and vice verse, while cooperatingat the ends of its path of travel with a reversing valve which connectsa chamber between said cylinder and piston with either the internalpressure of the filter or atmospheric pressure.

Another characteristic of the filter described in application Ser. No.792,696, resides in the provision of a ratchet device which drives saidpressure unit in rotation from one column to the next during the strokeof the piston in one direction, whereas a counter-current injection ofcleaning liquid takes place during the stroke of the piston in theopposite direction, during which the pressure unit remains stationary inalignment with a predetermined column which is to be cleaned.

The present invention is directed to certain improvements to thepressure unit and to the reversing valve which cooperates with thepiston of this pressure unit.

In the first place, the differential or stepped piston described in theprevious patent is replaced by a piston having a constant diametercooperating with a cylinder which is also of constant diameter.

In this new arrangement the spring which cooperates with the piston,instead of being in compression during countercurrent cleaning whichtook place in the previously described apparatus, when the differentialchamber of the piston was in communication with the atmosphere, inresponse to the higher internal pressure prevailing inside the filterand opposing to this compression a resistance less than the differencebetween said internal pressure and atmospheric pressure, creates on thecontrary only the excess pressure necessary counter-current cleaningduring the stroke of the piston in which its rear face is subjected tosaid internal pressure, while the difference between the internalpressure of the filter and atmospheric pressure compresses said springduring the stroke of the piston in the opposite direction.

Moreover, the operation of the reversing valve has been improved and,instead of actuating this valve by means of a coil spring obliquelyengaging a projection, it is actuated by a leaf spring cooperating witha pivotal member. The amplitude of of the pivotal movement of thismember is limited by suitable stop means and said pivotal member iscoaxial with a cam mounted to turn freely about its axis and located ina recess in said pivotal member. This cam is adapted to engage an axison which one of the arms of the leaf spring is mounted at the two endsof the path of travel of the piston so as to prevent said pivotal memberfrom reversing the position of the reversing duct until the piston hasreached one of the ends of its stroke.

Another improvement embodied in the filter according to the presentinvention resides in the provision of a check valve permitting the exactregulation of the quantity of cleaning fluid counter-currently injectedinto each column.

Finally, the device for rotating the pressure unit which comprised twocooperating superposed discs superposed along radial generatrices hasbeen replaced by a more accurate device comprising an eccentric camdriven by a gear fixed to the piston of said pressure unit and intowhich a driving pawl may be projected by a radial spring, said pawlbeing adapted to slide on the outer surface of the teeth of a ratchetwheel coaxial with said cam without driving it in rotation during onedirection of rotation of the cam, while the end of this pawl drives apressure member fixed to the said ratchet member during the rotation ofthe cam in the other direction, corresponding to the compression phaseof the spring.

The characteristics of the new filter according to the present inventionwill be better understood from a reading of the following description ofa preferred embodiment of this filter, given purely by way of exampleand with reference to the accompanying drawings, in which:

FIG. 1 is a diametrical sectional view of the new filter with its upperpart constituted by said pressure member and with the piston representedin a position corresponding to the end of the stroke in which a columnis cleaned by counter-current flow;

FIG. 2 is an elevational view of the pressure member showing thevertical arm fixed to the piston which controls the reversal of thevalve;

FIG. 3 is a cross sectional view taken along the line III-III of FIG. 2showing the pressure member being driven in rotation during the returnstroke of the piston after the counter-current injection of cleaningliquid;

FIG. 4 is an elevational view of the reversing valve shown a littlebefore release of the cam permits the reversal of the valve;

FIG. 5 is a view similar to FIG. 4 but showing the position at the endof the cleaning of a column;

FIG. 6 is a view showing the same reversing valve while the spring isbeing compressed between two consecutive cleansings; and

FIG. 7 is a view similar to FIG. 6 showing the position of the piston atthe end of its stroke after reversal of the valve.

It will be seen from FIG. I that the space 2 which is in communicationwith the inside of the piston l is connected through a duct 6 to thespaces 3 and 4 which are connected to each other by an opening 5 and aresubject to the internal pressure of the filter. The piston 1reciprocates inside the cylinder 7 and is actuated by a spring 8, whenthe piston l is subjected on its two surfaces to the same pressure, orby the combined effect of atmospheric pressure on the front face of thepiston, the internal pressure of the filter on its rear face, and theresistance of the spring to compression. The spring 8, when expanded,creates in the space 9 an excess pressure which closes the check valve10 biassed by the spring 11. The excess pressure in the chamber 9 causesthe counter-current cleaning of a column in the direction of the arrow12. When the piston 1 is at its extreme right position, the valve 6 alsovisible on FIG. 1 assumes a position in which its duct 64 is verticaland connects the chamber 2 with atmospheric pressure. The pressure inthe spaces 3 and 4 is then greater than atmospheric pressure and thecheck valve opens and the pressure in the chamber 9 in excess of theatmospheric pressure in chamber 2 compresses the spring 8.

The piston 1 then returns to the left until, as will be hereinafterseen, the valve member 6 again reverses and connects the chamber 2 tothe internal pressure of the filter which prevails in the chamber 9.

The spring 8 may then expand and return the piston l to the right withcounter-current cleaning of another column and closing of the checkvalve 10 biassed by the spring 11.

The new filter operates as follows: the filtered fluid rises normally inthe different filtering columns 12 in the direction of the upper part ofthe filter, except for the column which is represented on the right partof FIG. 1, in which said filtered fluid flows out in the oppositedirection of the lower part of the filter during its cleaning.

The separation between the fluid to be filtered and the filtered fluidwhich is lodged in the upper part of the filter, above the filteringcolumns 12, is obtained by a joint 13 which is compressed when thefilter is closed at its upper part.

The filtering columns 12 are joined together and with a plate 14 bymeans of distance-pieces 15.

The plate 14 is joined also with a plate 16 by means of a central bolt17 which applies said plate 16 against a shoulder of a peripheral ring18.

The plate 16 can not rotate with respect to the plate 14, and isconnected with said plate by a pin 19.

The filtering columns 12 are hold at their lower part by means of aplate 20 and by screws 150 which cooperate with the lower part of thedistance-pieces 15.

Further, the tightness of the two ends of the columns 12 is ensured bymeans of screws 21 which are provided with counter-nuts 21a.

It is to understand that the column represented on the right part ofFIG. 1 is, during its cleaning by a counter-current, right in front of aring 22 in the central part of which passes said counter-current offluid produced by said pressure member which constitutes the upper partof the filter.

Said ring 22 is applied against the plate 14 by a spring 23.

At the lower part of the filter is provided a conical bottom which endsin the form of a ring 24.

Said ring can be sealed by a bush or by a cock, to allow the dischargeof residual particles which fall in said conical bottom, especiallyduring the cleaning of the columns 12 without reaching the otherfiltering columns.

Besides, the fluid to be filtered enters in the direction of the arrows25, passes in the columns which are not submitted to a counter-current,in the direction of the arrows 26, the filtered fluid going up along thearrow 27 and going out of the filter in the direction of the arrow 28.

The filtered fluid, which is in the space 3 can pass through thesubsidiary shell 6, in the direction of the arrow 29, to balance thepressure of the same fluid which acts on the right part of the piston 1during the cleaning.

The spring 8, during said balance, creates the return to the right ofthe piston 1, and generates the countercurrent of filtered fluid in theright column 12 which should be cleaned, said counter-current having thedirection of the arrow 30.

The cleaning which is carried out on the external wall of said rightcolumn 12 is obtained by a flowing of filtered fluidin the direction ofthe arrow 31, and the impurities which are separated from said columnfall in the conical bottom of the filter and accumulate at the level ofthe ring 24, as was previously mentioned.

The axis 32 of the reversing mechanism of the subsidiary shell 6 is alsorepresented on FIG. 1.

The rotation of the pressure unit during the compression of the spring 8is produced by the ratchet wheel 33 shown in FIG. 3.

The roller 34 which is attached to the piston l by the vertical member35 shown on FIG. 2 drives the cam 36 provided with groove 36a. Thisrotation is transmitted to the ratchet wheel 33 by the pawl 37 which ismounted to swing about the axis 38 and is biassed by a spring 39 againstthe ratchet wheel 33.

The rotation of the cam 36 is thus transmitted to the ratchet wheel 33during the return of the piston to the left of FIG. 1, whereas, when thepiston moves to the right, that is to say, during the period in whichliquid is injected counter-currently for cleaning purposes, the rotationof the cam 36 has no effect on the ratchet wheel 33, since the pawl 37glides along the teeth of the ratchet wheel 33 until it reaches the nextnotch, after having rotated through an angle which, as shown in FIG. 3is 30, assuming a filter having 12 equal distance columns.

FIGS. 4 and 7 show the upper part 35a of the member 35.

The leaf spring 40 pivots about the axis 41 fixed to a bell-shapedmember 42 provided with a recess 42a inside which a cam 43 may pivotwithin certain limits about an axis 32.

During the movement of the piston 1 toward the right in response topressure by the spring 8, the spring 40, as a consequence of themovement of the part 35a of the member 35 passes from the relativelyclosed position shown on FIG. 7 to the substantially open position shownon .FIG. 4 in which the two arms of the spring are spaced by a maximumdistance.

When the vertical member 35 has moved sufficiently to permit the cam 43to escape from the roller 44 fixed to the part 350 of this verticalmember, with which it cooperates, the spring 40 closes, causing themember 42 to pivot, together with the cam 43, into the position shown inFIG. 5.

While the spring 8 is being compressed, that is after swinging of themembers 42 and 43 and inversion of the valve member 6, the spring 40opens again, as shown on FIG. 6, but the movement to the left of thepart 35a of the vertical member 35 causes progressive pivoting of thecam 43 with respect to the member 42 without the member 42 being able tomove substantially from the position which it occupies in FIG. 5. It isonly when the member 35 reaches its extreme position to the left, shownin FIG. 7, that the cam 43 may escape from the roller 44 and that theleaf spring 40 may close while swinging the member 42 to the left untilthis member reaches an adjustable stop 45.

In like manner, FIG. 5 shows that the member 22, after swinging,encounters another adjustable stop 46. Since the stops 45 and 46 areadjustable and limit the path of travel of the member 42, the length ofthe angular path of travel of the valve 6 may be exactly regulated so asto place the chamber 2 in communication with atmospheric pressurethrough the duct 6a and the valve 6 during the course of return of thepiston 1.

The function of the check valve 10, which closes during counter-currentcleaning, that is to say during the stroke of the piston to the right,and which opens when the pressure inside the chamber 9 becomessubstantially less than the internal pressure of the filter in responseto the return of the piston l, is, of course, obvious.

The internal pressure of the filter is always enough, in proportion tothe atmospheric pressure on the opposite side of the piston, tosuccessively overcome the force exerted by the spring 11 and then thatof the spring 8.

It will of course be appreciated that the embodiment which has just beendescribed may be modified as to detail without thereby departing fromthe basic principles of the invention as defined by the followingclaims.

What is claimed is:

1. In a self-cleaning filter of the type comprising a plurality ofvertical filter columns equidistantly arranged about a vertical axis anda rotatable pressure unit for forcing a cleaning fluid into each columnsequentially and counter-currently, which unit comprises a cylinderhaving a horizontal axis and a piston mounted to reciprocatetherewithin, said cylinder being mounted to rotate about said verticalaxis to bring the space between said piston and one end of said cylinderinto communication with each column successively, a spring biassing saidpiston toward said one end of said cylinder, valve means connected toalternately subject the face of said piston remote from said one endalternately to the pressure prevailing within said filter and toatmospheric pressure, and means actuated by said cylinder at each end ofits stroke for automatically reversing said valve means, the improvementaccording to which the other face of said piston is constantly subjectedto the pressure within the filter, so that the pressure applied toproduce counter-current cleaning is supplied solely by said spring, whenboth faces of the piston are subject to the pressure within the filter.

2. Filter as claimed in claim 1 which comprises a check valve foradmitting fluid under the pressure prevailing within said filter to saidone end of said cylinder, said check valve being spring biassed to aclosed position, and positioned to be automatically closed when thepressure prevailing within said filter is applied to both faces of saidpiston.

3. Filter as claimed in claim 1 in which said valve means comprises avalve member which turns through an angle of substantially 60 betweenits two positions.

4. Filter as claimed in claim 3 comprising a leaf spring for actuatingsaid valve member, said leaf spring having a first arm connected at itsouter end to vertical means carried by said piston and a second armconnected at its outer end to a member mounted to pivot about a fixedaxis, said member comprising a recess receiving a cam mounted to swingthrough an angle of substantially about the same axis, and having an endprojecting from said recess which contacts a roller mounted on saidvertical piston-carried means so as to prevent said member from swinginguntil said piston is at one of the ends of its path of travel, at whichtime the ends of said spring arms are maximumly separated, andadjustable stop means limiting the swinging movement of saidrecess-comprising member.

5. Filter as claimed in claim 4 in which said vertical member carries atits lower end a roller which turns a cam mounted to rotate coaxially ofa ratchet wheel attached to said pressure unit said cam carrying a pawlwhich is spring-biassed against the teeth of said ratchet wheel, wherebysaid piston, through said vertical member, cam and pawl, turns saidratchet wheel and pressure unit while the piston is moving to compressthe spring which biasses, but has no rotating effect on said pressureunit when said piston is moving in the opposite direction, in which casesaid pawl slides on the teeth of said ratchet wheel.

1. In a self-cleaning filter of the type comprising a plurality ofvertical filter columns equidistantly arranged about a vertical axis anda rotatable pressure unit for forcing a cleaning fluid into each columnsequentially and countercurrently, which unit comprises a cylinderhaving a horizontal axis and a piston mounted to reciprocatetherewithin, said cylinder being mounted to rotate about said verticalaxis to bring the space between said piston and one end of said cylinderinto communication with each column successively, a spring biassing saidpiston toward said one end of said cyliNder, valve means connected toalternately subject the face of said piston remote from said one endalternately to the pressure prevailing within said filter and toatmospheric pressure, and means actuated by said cylinder at each end ofits stroke for automatically reversing said valve means, the improvementaccording to which the other face of said piston is constantly subjectedto the pressure within the filter, so that the pressure applied toproduce counter-current cleaning is supplied solely by said spring, whenboth faces of the piston are subject to the pressure within thefilter.
 1. In a self-cleaning filter of the type comprising a pluralityof vertical filter columns equidistantly arranged about a vertical axisand a rotatable pressure unit for forcing a cleaning fluid into eachcolumn sequentially and counter-currently, which unit comprises acylinder having a horizontal axis and a piston mounted to reciprocatetherewithin, said cylinder being mounted to rotate about said verticalaxis to bring the space between said piston and one end of said cylinderinto communication with each column successively, a spring biassing saidpiston toward said one end of said cyliNder, valve means connected toalternately subject the face of said piston remote from said one endalternately to the pressure prevailing within said filter and toatmospheric pressure, and means actuated by said cylinder at each end ofits stroke for automatically reversing said valve means, the improvementaccording to which the other face of said piston is constantly subjectedto the pressure within the filter, so that the pressure applied toproduce counter-current cleaning is supplied solely by said spring, whenboth faces of the piston are subject to the pressure within the filter.2. Filter as claimed in claim 1 which comprises a check valve foradmitting fluid under the pressure prevailing within said filter to saidone end of said cylinder, said check valve being spring biassed to aclosed position, and positioned to be automatically closed when thepressure prevailing within said filter is applied to both faces of saidpiston.
 3. Filter as claimed in claim 1 in which said valve meanscomprises a valve member which turns through an angle of substantially60* between its two positions.
 4. Filter as claimed in claim 3comprising a leaf spring for actuating said valve member, said leafspring having a first arm connected at its outer end to vertical meanscarried by said piston and a second arm connected at its outer end to amember mounted to pivot about a fixed axis, said member comprising arecess receiving a cam mounted to swing through an angle ofsubstantially 150* about the same axis, and having an end projectingfrom said recess which contacts a roller mounted on said verticalpiston-carried means so as to prevent said member from swinging untilsaid piston is at one of the ends of its path of travel, at which timethe ends of said spring arms are maximumly separated, and adjustablestop means limiting the swinging movement of said recess-comprisingmember.